Un-brittle-ify backend E2E tests and have them run by default again in CI (#397)

* test running tests

* Add delay so that core knows about node before feed subscribes to limit chance of race

* move delaye to the right place

* Don't do expensive docker step untill we will be pushing the image

* docker test skipped as hoped, so push to 'true'

* just remove docker steps in github CI entirely since they aren't needed by anything (gitlab CI does this stuff now)

* run CI on pull requests too to catch PRs from forks

.github/workflows/frontend.yml

@@ -9,6 +9,11 @@ on:
       - '.github/workflows/frontend.yml'
       - 'frontend/**'
       - '!backend/**'
+  pull_request:
+    paths:
+      - '.github/workflows/frontend.yml'
+      - 'frontend/**'
+      - '!backend/**'
 
 defaults:
   run:
@@ -41,18 +46,3 @@ jobs:
 
     - name: Build
       run: yarn build
-
-    - name: Login to Dockerhub
-      uses: docker/login-action@v1
-      with:
-        username: ${{ secrets.DOCKER_USERNAME }}
-        password: ${{ secrets.DOCKER_PASSWORD }}
-
-    - name: Build and Push template image
-      uses: docker/build-push-action@v2 # https://github.com/docker/build-push-action
-      if: matrix.node-version == '12.x'
-      with:
-        context: './frontend'
-        push: ${{ startsWith(github.ref, 'refs/tags/') }}
-        tags: parity/substrate-telemetry-frontend:latest
-        # add_git_labels: true